View Full Version : O2 sensors on FFR side pipes?
tcsracing1
10-20-2017, 07:24 PM
I have 5.0L motor with factory fuel injection.
Do you install bungs on the sidepipes for O2 sensors?
I have 5.0L motor with factory fuel injection.
Do you install bungs on the sidepipes for O2 sensors?
The O2 sensor should go in the header or J-Pipe before the exit to the side pipes.
tcsracing1
10-20-2017, 09:40 PM
The O2 sensor should go in the header or J-Pipe before the exit to the side pipes.
thanks, i wasnt sure as the headers come already coated and i was afraid to spoil them.
AC Bill
10-20-2017, 11:33 PM
Some fellows installed the 5.0's O2 sensors in the side-pipes, just after the collector. This was to try and get an average reading on all cylinders. There was some questions posed as to if this position maybe to far away to get an accurate reading, as the sensor don't get hot enough. Some sensors were designed with a element system to heat them up. I don't recall hearinag anyone that mounted them there complain, other than they were visible, and potentially could get damaged.
The other choice was to install the sensor in just one of the header pipes, (per side), using the recommended distance of 14-16" from the head. This ensured the heat needed for accurate readings, but you only get the reading from one cylinder. So the ECM would adjust the lean/rich condition for that entire bank of cylinders, based on that one cylinder. The #4 and #8 cylinders were traditionally used for the sensors.
I did that, as did many builders, and can't say it has ever cause an issue. I drilled the hole, and welded in the bung, then afterward sprayed the area with VHT paint that was virtually the same color as the ceramic coating. Many years, and miles later, there has been no issue with the coating, or the VHT paint, and the engine runs great..
CraigS
10-22-2017, 06:44 AM
There is a lot of debate on this subject. I like them where AC Bill put them. Easy to do and easy to run the wires w/o needing extensions.
David Williamson
10-22-2017, 08:23 AM
I did the same as AC Bill when I built my mkll in 2004 - many years and over 30,000 miles it works
David W
Big Blocker
10-22-2017, 02:17 PM
I went to the other extreme . . . I welded two collectors together (back-to-back) to form a "venturi" at their center, added a bung for the O2 at that junction. O2 is 14" from head and samples all four cylinders. Luckily, I wasn't working with ceramic coated headers yet, just bare steel. Many of the header vendors are now supplying this type of 4-into-4 headers . . .
75761
Doc